So-called flexible endoscopes include means for illumination of a field to be studied, an optical system to observe the field, and means to cause controlled bending of the endoscope. The elements which relate to illumination and observation are usually in the nature of flexible optical fibers. Especially the fibers used for observation are generally very small in size and large in number. They require lateral support and enclosure to maintain an orderly array, and to reduce the rate of breakage of the fibers.
These elements and their support must together form an endoscope of minimal diameter. Endoscopes are frequently inserted into very small passages and orifices, and any reduction in lateral dimensions, not made at the cost of reduction of reliability or function, is welcome.
Articulations comprising short segments of tubing that are pivotally jointed together are known. Customarily they are joined by headed rivets which act as pivots. These joinder means involve either an enlargement on the outside of the vertebra, or on its inside, and sometimes on both. On the inside it reduces the cross-section which accommodates the endoscope elements, and thereby requires a larger tube diameter for an equivalent result. On the outside it contributes an enlargement or disruption. Either way, the result is a larger-diameter endoscope.
Alternate joinder means of the short segments are also known and include interlocking tab type designs, stay wire type designs, ball and socket designs, and others. These joinder means also involve an enlargement of the vertebrae joint.
It is an object of this invention to provide an articulated tubular vertebra without objectionable protuberances either inside or outside of the pivot means which joins the tubular segments, whereby to provide joinders and joints of minimal radial dimension (thickness), and thereby an articulation of minimal external diameter for a given useful internal diameter.